Emission Questions

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Joined
Feb 6, 2007
Threads
4
Messages
53
Location
Vacaville, CA
Hello, I have a 85 w/ 5 speed and am in the process of trying to pass smog.

Question #1 On the 2 vacuum hoses that leave the distributor cap, one goes to the VCV (vacuum control valve) the other is to go to the air filter, I cannot seem to find the fitting for it , the only nipples I have found (on the air filter housing) are for the HIC (Hot Idle Compensation) valve. Is there a fitting I'm missing, I failed the visual part on that'

Question #2 Passed the 15 mph @ 1756 rpm's the numbers are...

CO2 14.43 / O2 1.01 / HC 63 / CO .27 /NO 118

FAILED the 25 mph @ 1691 rpm's

CO2 14.00 / O2 0.47 / HC 13 / CO 1.15 / NO 72

After the hose is routed correctly any clues on where to start?
Thanks, Scott
 
high CO indicates that either the air injection system is not working correctly, or the catalytic converter is not working correctly. Your residual O2 at 25mph is a little low, so I would start with checking out the AI system.

you can download a copy of the emissions manual from this post: IH8MUD.com - View Single Post - Rough Idle / Dies at Stops / Carb Issues

The schematic below shows how the distributor cap vent should be connected. The tube circled in red gets connected to a port on the top of the air cleaner. The "filter" is actually mounted from behind the firewall near where the glove box is. from the engine compartment, you will just see a nipple sticking out, if nothing is connected to it. If you can't find it, take some pic's and post up.
vacuum routing.JPG
 
Interesting failure, given the transmission was shifted to maintain approximately the same RPM at 15mph.

You lost a bit of catalytic efficiency at 25mph, the CO2 dropped slightly and the O2 dropped significantly, but not to the point of alarm about the AIR system.

The only thing I can think of that you can check externally is for an air restriction in the air filter assembly: inlet plugged, defective thermostatic valve, plugged air filter.

I am going to suggest the carburetor is adding too much fuel, as excessive CO is used to determine partially burnt fuel leaving the engine. I was not there, but it is possible the 25mph part of the test required more throttle angle to maintain the speed, which would not ordinarily be a problem. But if the carburetor has a defective cruise circuit (blocked emulsion jets, wrong main jets) or leaking accelerator pump, then it would have higher than normal CO emissions as the throttle angle increased.

Suggestion: Return to a smog station and run the test again in simulation mode. Try to reproduce the readings to see if there is a relation between the throttle angle and the CO readings.

Good luck and please report your discoveries and hopefully, successes!

Edit: A retest may discover the test was done such that a failure was introduced. Being wild with the throttle and making sudden throttle angle changes can cause a false failure.

Rick
 
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Gentlmen-Thanks for the quick replies and thoughts.

2mbb - I have the emissions manual and the diagram on the top of the fender well both state that the hose (90445-12046) goes to the "filter", Is there a separate filter located on the fire wall?

rchalmer3 - My thoughts exactly throttle angle, forced failure.I am in the process of cleaning the K&N, I didnt really notice any major restrictions. Your thoughts on throwing a stock filter on for the test.

Also the truck was from Texas and has a federal schematic, has a header and "Downey hot air riser kit", (I know, and he failed me for the vacuum hose) and K&N filter. The site is a " test only" site, and does not do repairs.

Any other thoughts are welcome.
Scott
 
filter 17810a shown in the schematic above is a filter that is mounted from inside the passenger compartment and the nipple only sticks through the fire wall. It is located just about behind the glove compartment (right side of the engine).

The hose 90445-12046 connects to the air cleaner. There should be a port on the top part of the air cleaner that points toward the right fender. the port is shown in the first picture in the thread below. The proper connection is shown in the last picture in the same thread. ignore the pictures in between because they are not the correct tube routing.

https://forum.ih8mud.com/60-series-wagons/366588-anybody-know-what-connects.html
 
filter 17810a shown in the schematic above is a filter that is mounted from inside the passenger compartment and the nipple only sticks through the fire wall. It is located just about behind the glove compartment (right side of the engine).

The hose 90445-12046 connects to the air cleaner. There should be a port on the top part of the air cleaner that points toward the right fender. the port is shown in the first picture in the thread below. The proper connection is shown in the last picture in the same thread. ignore the pictures in between because they are not the correct tube routing.

https://forum.ih8mud.com/60-series-wagons/366588-anybody-know-what-connects.html
Found the nipple. I also figured out that "filter" and "air cleaner" are 2 different items, (never assume). Thank you for your patience, off to the DMV to get my ext paperwork, than back to the smog station.
Scott
 
After a busy weekend, and back at work I can now post the results of my last attempt and plan my attack on the rig.

Visual-PASS, Functional - PASS, Emissions - FAIL

New smog station (other one didn't have any appts open till 6/9) new tech.

15 mph @ 1735 rpm / CO2 13.4 / O2 1.2 / HC 121 / CO 0.79 / NO 130 / PASS

25 mph @ 1672 rpm / CO2 13.3 / O2 0.6 / HC 31 / CO 1.50 / NO 66 / FAIL


Standing By
Scott
 
Almost exactly as before. If you did anything to the vehicle between tests, the work did nothing to alter the results!

Notice how the HC and NOx drop with the added fuel (CO). Your motor likes the fuel!

I stand by what I posted earlier, you are likely facing an internal carburetor issue. The few external factors that cause a rich mixture are easily checked, then it's carb overhaul time.

Rick
 
Thanks for your time again, No changes other than proper vacuum line placement. Just had to get it to pass the visual, to enable me to apply for "CAP". The state only gives you 60 days, and now they charge you 50.00 for a temp registration. After that you have to get a day pass every time you want to drive/move your truck. What a pain. My gut is saying its the carb. I searched "high CO" and the results were the carb, Before a rebuild I may just try a good adjustment for a baseline. I read a thread and think thats possible :wrench::wrench: I would like to fix the problem, rather than mask it with a new cat like the State has done before. Any thoughts are welcome.

Scott :flipoff2:
 
Engine temperature at test?
How long running before test?

My results:
15 mph @ 1889 rpm / CO2 10.6 / O2 5.7 / HC 125 / CO 0.13 / NO 205 / PASS
25 mph @ 1796 rpm / CO2 10.6 / O2 5.4 / HC 95 / CO 0.50 / NO 161 / PASS

Before a smog check I drive for at least a half an hour on the freeway @ 65 -75 mph, do an oil change before, tune up and err the ignition timing about 1 degree less (NOX) than spec.
 
Check that the hot air intake flap is opening once it is warm and you are getting cold air from the fender. Also I would stick in a paper filter. You got to rule one thing out at a time.
 
dorcom- On the timing... 6'BTDC ??. The run time prior was about 5-10 min, it was up to operating temp per the dash gauge. Copy fresh oil change and tune up.

NorcalFJ60- I'll check the hot air intake flap, and paper filter.

Thanks, Scott
 
dorcom- On the timing... 6'BTDC ??. The run time prior was about 5-10 min, it was up to operating temp per the dash gauge. Copy fresh oil change and tune up.

NorcalFJ60- I'll check the hot air intake flap, and paper filter.

Thanks, Scott

Scott
Yes, set to 6'BTDC. (Factory spec is 7'BTDC @ max 950 rpm vac advance hose blocked/off)

Warm up way to short! give her a 1/2 hour!
Your driving an old vehicle! How does it drive in general? Notice anything
e.g. hesitation, etc.? Your comparatively low NOX points to EGR open (too soon), if that happens
vehicle hesitates, as counter effect/reaction accelerator will be pushed more = CO more (rich)

CAT's usually effectively fully work after about 20 min.
Put new spark plugs in, replace air filter or even remove it.
Choke fully open?
Idle mix screw adjusted properly? (err on the lean side)
Run the "guaranteed to pass" stuff in tank before.
Get Shell or Chevron gas, get premium (Yes it is a ROZ 91 engine!) their whatever additive in the gas helps too.
With a little work you'll pass in flying colors every time like I do!
I'm in SF where are you?

Rob :steer:
 
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Thanks again. It does hesitate and fills like its too rich, I'll check that out. Ran the liquid smog products and filled with premium gas. I'll make these changes and cross my fingers. I'm in Vacaville.
Scott:flipoff2:
 
Thanks again. It does hesitate and fills like its too rich, I'll check that out. Ran the liquid smog products and filled with premium gas. I'll make these changes and cross my fingers. I'm in Vacaville.
Scott:flipoff2:

Whatever happened with this? :confused:
 

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